I have Helianthus angustifolius, Agalinis purpurea, Bidens aristosa, Solidago sp., Verbena bonariensis, Pavonia hastata. Let me know if you would be interested in trading with me. Thank you. Don Here is a link that might be useful: My Tradelist

That is awfully slow Feijoa growth for ten years. Mine would grow over two feet per year if I didn't pinch the new growth when at one foot. All this growth with only a couple of inches of composted manure added every few years. You imply your plants bloom but do not mention how much. When you tap on a blooming feijoa branch, pollen does fly off. 50 yards is too far for reliable wind pollination. You do not even need a brush to hand-pollinate these. Just thoroughly molest the blooms by fingertips, touching all the flower parts (except the petals). 2 or 3 seconds per blossom is enough, just concentrate on the fully-open blooms that have yellow pollen on the stamen tips. Once the stamens start to fall off the flower, it is too late. If your plants are seedlings, extra effort may be in vain. I've seen quite a few plants up here in Portland refuse to fruit.

I see a number of those problem fruits every year, they don't fully fill out and remain hard inside with internal fissures and brownish, leathery pulp areas. A late bloom or an early freeze make this problem worse. It could well be a pollination issue.

In Central Florida near the East Coast we have a big problem with fruit flies both the Caribbean variety and the standard fruit fly. I have a home orchard with two guava trees. One is a Ruby Supreme guava and the other a Barbie Pink guava. The Ruby Supreme was under incessant attack by the fruit flies. Nothing I tried including spraying or using traps with apple cider vinegar and dish soap could eradicate them. Actually, the latter seemed to be effective against the Caribbean fruit fly but not against the standard fruit fly. To make a long story short I uprooted and destroyed the Ruby Supreme guava tree. It was painful because I love guavas but it's just too much trouble dealing with those pesky critters. The Barbie Pink guava is still in my orchard but I have noticed the fruit flies attacking it. So I removed all the fruit and threw them away. I will most likely destroy that tree also later this winter or maybe repot it into a half whiskey barrel planter. It might make a good gift for my sister if/when she buys her own home. Or if I could get a greenhouse installed in my yard then I could isolate the tree from the flies. I also have the feijoa selliowana (aka the pineapple guava) tree in my garden. The 5 of them are in pots and I had thought about making a hedge out of them. They don't seem to tolerate the blistering summer heat of Florida so they need to be in shady spot during the late afternoon hours. I am not sure if the fruit fly can attack the pineapple guava because it seems they have a much thicker peel than the ordinary guavas. A thick peel is the best line of defense against fruit flies I hear. I was hoping someone on this forum could confirm if they are resistant to fruit flies or not. But it has to be a report from someone who lives in an area that is prone to that sort of infestation.